B-doped graphitic carbon nitride as a capacitive deionization electrode material for the removal of sulfate from mine wastewater

Abstract

BackgroundBoron doping can replace C/N atoms to form nitrogen defects or lattice distortions without destroying the original skeleton of g-C3N4, which may improve the electrode transfer efficiency and electrosorption performance of the materials. B-doped would make g-C3N4 more suitable for treating SO42− in mine wastewater as a capacitive deionization electrode material. MethodsMelamine and boric acid were used as raw materials to prepare a B-doped g-C3N4 electrode material. The electrosorption experiment was carried out and the materials were characterized. Significant findingsBoron-doped graphitic carbon nitride (B-doped g-C3N4) was prepared for capacitive deionization (CDI) to remove SO42− from the mine wastewater for the first time. After optimization, the electrode exhibited a maximum electrosorption capacity of 14.70 mg/g. A series of reactions of boric acid at high temperatures enlarged the available space and pore size in g-C3N4. B replaced C atoms to form structural defects, increasing the electron transmission efficiency and specific capacitance. After 25 cycles of CDI system operation, the removal rate of SO42− in the mine wastewater reached 75.4%. This study improved the application potential of B-doped g-C3N4 in capacitive deionization and the treatment of mine wastewater.